A Concurrent Exposure to Arsenic and Fluoride from Drinking Water in Chihuahua, Mexico

Inorganic arsenic (iAs) and fluoride (F(−)) are naturally occurring drinking water contaminants. However, co-exposure to these contaminants and its effects on human health are understudied. The goal of this study was examined exposures to iAs and F(−) in Chihuahua, Mexico, where exposure to iAs in drinking water has been associated with adverse health effects. All 1119 eligible Chihuahua residents (>18 years) provided a sample of drinking water and spot urine samples. iAs and F(−) concentrations in water samples ranged from 0.1 to 419.8 µg As/L and from 0.05 to 11.8 mg F(−)/L. Urinary arsenic (U-tAs) and urinary F(−) (U-F(−)) levels ranged from 0.5 to 467.9 ng As/mL and from 0.1 to 14.4 µg F(−)/mL. A strong positive correlation was found between iAs and F(−) concentrations in drinking water (r(s) = 0.741). Similarly, U-tAs levels correlated positively with U-F(−) concentrations (r(s) = 0.633). These results show that Chihuahua residents exposed to high iAs concentrations in drinking water are also exposed to high levels of F(−), raising questions about possible contribution of F(−) exposure to the adverse effects that have so far been attributed only to iAs exposure. Thus, investigation of possible interactions between iAs and F(−) exposures and its related health risks deserves immediate attention.